Accelerating Thrombus Resolution Through Augmentation of p53 Activity

ABSTRACT

A novel function for the p53 gene related to resolution of deep venous thrombosis is disclosed herein. Lack of the p53 gene results in impaired thrombus resolution in a clinically relevant in vivo model of deep venous thrombus resolution. It is further shown that augmentation of p53 activity with quinacrine accelerates thrombus resolution in vivo, and that this beneficial effect is completely dependent on p53. p53-based therapy is therefore provided to accelerate thrombus resolution in patients, and to prevent or ameliorate the debilitating long-tem complications of deep venous thrombosis such as post-thrombotic syndrome.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH OR DEVELOPMENT

This invention was made with Government support under Grant No.HL083917,awarded by National Institutes of Health. The Government hascertain rights in this invention.

FIELD OF THE INVENTION

The present invention relates to medical treatment. Specifically, thepresent invention relates to pharmacological and/or molecular treatmentof thrombosis though augmentation of p53 activity to accelerate theresolution and healing of the thrombus.

BACKGROUND OF THE INVENTION

Blood clots in veins, also known as deep venous thrombosis, affects 1-2million Americans per year. Deep venous thrombosis can lead to pulmonaryembolism, in which the thrombus detaches and travels to the lungs whereit can cause fatal cardiopulmonary complications. Pulmonary embolismfrom deep venous thrombosis is the leading preventable cause ofin-hospital death and accounts for greater than 200,000 deaths per yearin the U.S. The standard treatment for deep venous thrombosis isimmediate anticoagulation which prevents the thrombus from propagating(growing) and subsequently detaching and inducing pulmonary embolism.Anticoagulation, if instituted promptly, is highly effective atpreventing pulmonary embolism. Deep venous thrombosis has additionaldetrimental effects on the vein wall, however, and these changes cancause significant disability and disease. Delayed resolution (healing)of the thrombus results in vein wall and venous valve damage, andeventually can cause post-thrombotic syndrome in 25-75% of patientsmonths to years after a deep venous thrombosis.

Post-thrombotic syndrome can include symptoms of swelling, pain and skinchanges up to and including chronic non-healing ulcers of the skin.Post-thrombotic syndrome is due to increased venous pressure in theveins of the leg, and is caused by either loss of the venous valves dueto scarring or persistent obstruction of the vein lumen by the thrombus.It is estimated that 2% of total health care costs in the United Statesare due to treatment of venous leg ulcers, and numerous studies havedocumented poor quality of life, persistent disability and repeatedhospital admission in those patients suffering from venous leg ulcers,which are the most severe manifestation of post-thrombotic syndrome.Approximately 1% of individuals over the age of 65 have a venous legulcer per the General Practice Research Database.

These long-term complications of deep venous thrombosis have led tointerest in pharmacologic and mechanical therapy to either remove thethrombus or accelerate the body's healing or resolution of the thrombuswithin the vessel wall. Treatment of deep venous thrombosis within twoweeks of onset with thrombolytic therapy or mechanical thrombectomy ispossible in some cases, and early clinical trials indicate that earlyremoval of the thrombus results in improved long-term venous function inthe leg. Thrombolytic therapy consists of specific enzymatic agents(e.g. tissue plasminogen activator) which cleave the fibrin within thethrombus. Several means of mechanical thrombus removal are alsoavailable, including balloon catheter devices (Fogarty catheter), highspeed saline irrigation systems (Angiojet) and rotational wire/catheterdevices (Trellis). These devices can be combined with pharmacologicthrombolysis as discussed above for greater potential efficacy.

The limitation of both pharmacologic and mechanical thrombectomy is thatthey are generally are ineffective in patients who present with thrombusof greater than 2 weeks duration. This is due to the natural change inthe composition and structure of the thrombus itself over time, wherethe initial fibrin-rich mass is gradually replaced with a firmer, morefibrotic ingrowth of tissue. This fibrotic tissue is not responsive tothe enzymatic action of pharmacologic thrombolysis and is also lessamenable to mechanical thrombectomy methods. Thrombolytic therapy has amoderate risk of complications including bleeding from the puncturesite, hematoma, rethrombosis and can also have rare but life-threateningcomplications (e.g. intracranial hemorrhage) which leads to caution inrecommending their wide use to treat deep venous thrombosis. Thus,current treatment strategies aimed at deep venous thrombosis are limitedto those patients who present for medical care within two weeks of theonset of the thrombosis, which is a subset of all patients with deepvenous thrombosis. Both pharmacologic and mechanical thrombolysis areinvasive procedures and carry the risk of serious complications.

Another strategy to decrease the detrimental effects of deep venousthrombosis on the vein wall and circulatory system is to accelerate theresolution of the thrombus by the body's own healing mechanisms. Theresolution of deep venous thrombosis in patients has been studied withvenography (which involves x-rays after injection of contrast materialinto the vein) as well as non-invasively with duplex ultrasoundtechnology. These studies have demonstrated variable resolution of theobstructive thrombus over time in patients, which is noted asrecanalization of the vein by either venography or ultrasound imaging.Those patients who demonstrate rapid resolution of the thrombusgenerally have improved clinical outcomes and less symptoms ofpost-thrombotic syndrome than patients with persistent venousobstruction noted by imaging studies.

A similar situation exists in the arterial circulation where thrombusresults in the blockage of arteries and decreased flow of oxygenatedblood to the downstream tissue. This is compensated for by collateralarteries which increase in size to allow circulation around theblockage. Some arterial thrombi are noted to recanalize over time,potentially allowing circulation through the previously blocked artery.As with deep venous thrombosis, arterial thrombosis can be treated withthrombolytic therapy if detected early, but no specific therapy existsto accelerate resolution of an arterial thrombus to increase thepotential chances of recanalization of the artery and restoration ofin-line blood flow.

The exact mechanisms of thrombus resolution are not well understood, asresolving deep venous thrombi are rarely if ever removed from patientsto allow pathological examination. Thus, our knowledge of the biologyand molecular mechanisms of thrombus resolution are largely derived fromexperimental animal models of deep venous thrombosis, in whichpathological examination of the thrombus at different time pointsreveals a defined cascade of biological events that contribute to theresolution process.

In rodent models of thrombus resolution, the inferior vena cava issurgically ligated to generate a thrombus immediately below theligature. This thrombus reaches a maximum size in 3-4 days and thenundergoes a reduction in size and volume over time. Pathologicalexamination of these thrombi over time demonstrate an early (1-2 days)infiltration of neutrophils into the initially fibrin- and red bloodcell-rich thrombus, followed by a subsequent infiltration of macrophages(after 3-4 days) and ingrowth of capillary blood vessels and depositionof collagen. Studies utilizing such rodent models of thrombus resolutionhave shown an important role for certain genes in the thrombusresolution process, including urokinase-type plasminogen activator andheme oxygenase. Experimental studies designed to improve resolution ofdeep venous thrombosis with exogenous therapy have shown that genetransfer of the vascular endothelial growth factor (VEGF) gene using anadenovirus injected into the formed thrombus results in improvement inthrombus resolution as measured by thrombus weight at a subsequent timepoint (Arteriosclerosis, Thrombosis, and Vascular Biology.2008;28:1753.). It should be noted that injection of experimentalthrombi with angiogenic peptide growth factors (VEGF protein rather thanan adenovirus) targeted to accelerate thrombus resolution did not resultin any improvement in the process of thrombus resolution. (J Vasc Surg.2004 September;40(3):536-42). Gene therapy with an adenovirus raisesserious issues of toxicity and safety of viral vectors and is currentlyfar from clinical use in patients. Treatment of animals with thecytokine macrophage chemotactic factor (MCP-1) does improve experimentalthrombus resolution although this agent is not approved for use inhumans (J Vasc Surg. 1999; 30: 894-899). Experimental animal studiesusing the widely available anticoagulant low molecular weight heparinhave shown no improvement in the resolution of an established thrombus,which correlates with the clinical data demonstrating that promptanticoagulation prevents pulmonary embolism but does not alter theresolution of the thrombus in the leg.

In summary, there is currently no specific pharmacologic therapydesigned to accelerate resolution of such an established venousthrombosis. The majority of patients with deep venous thrombosiscurrently do not receive thrombolytic therapy or mechanical thrombectomyas they present after the two week window of time in which this type oftherapy is effective at removing the thrombus. Thus, a large populationof patients are at substantial risk of long-term development ofpost-thrombotic syndrome. Post-thrombotic syndrome is a debilitatingcondition that affects ambulation, the ability to work and overallquality of life. There is no effective treatment for post-thromboticsyndrome once it is established. A pharmacological means of acceleratingthe resolution of deep venous thrombosis has the potential to improvevenous function by either decreasing the obstruction due to thrombusmass or preventing long-term scarring of the venous valves. There istherefore a definite need for pharmacologic or molecular means ofaccelerating the resolution of deep venous thrombi.

SUMMARY OF THE INVENTION

Disclosed herein is a novel function for the p53 gene, in the resolutionof deep venous thrombosis. Furthermore the disclosure demonstrates thataugmentation of p53 activity with a p53 activator such as quinacrineaccelerates thrombus resolution in vivo. Disclosed herein is p53-basedtherapy to accelerate thrombus resolution in patients, and therebyprevent or ameliorate the debilitating long-term complications of deepvenous thrombosis such as post-thrombotic syndrome.

Accordingly, a primary object of the present invention is to providepharmacologic or molecular means of accelerating the resolution of deepvenous thrombi.

Another object of the present invention is to define pharmacologicagents that accelerate resolution of a venous thrombosis and could beused systemically to treat a patient with a venous thrombosis to hastenits resolution and prevent secondary complications such as thepost-thrombotic syndrome.

Another object of the present invention is to define pharmacologicagents that accelerate resolution of an established thrombosis and couldbe used either alone or in conjunction with other agents to treat apatient with an established arterial thrombosis to increase potentialrecanalization of the thrombosed artery and restoration of blood flow.

Another object of the present invention is to identify pharmacologicagents that could be administered via a catheter or other drug deliverydevice (e.g. a perforated or hydrogel balloon) remotely within the bodyto an area of either venous or arterial thrombosis to accelerateresolution of the thrombosis to restore normal blood flow and preventsecondary complications (e.g. post-thrombotic syndrome for deep venousthrombosis).

Another object of the present invention is to define pharmacologicagents that could be applied to an intravascular device such as a stent,vascular graft or other implantable vascular prosthesis for the purposeof accelerating resolution of thrombosis either present at the time ofimplantation or that develop subsequently to the implantation.

Another object of the present invention is to identify genes importantin the process of thrombus resolution whose activity could be increasedin or around sites of arterial or venous thrombosis by gene transfer ofgenetic material encoding these genes using plasmid DNA, viral vectors,biophysical adjuncts or some combination thereof. The purpose of thisgene transfer would be to increase the expression of such genes toaccelerate resolution of the thrombus.

The present invention discloses a novel role for the p53 gene in theprocess of deep venous thrombi resolution and demonstrates thataugmentation of p53 function in a clinically relevant animal model ofthrombus resolution results in accelerated thrombus resolution.

It is disclosed herein that the p53 gene is activated during theresolution of venous thrombosis and plays an important role in theprocess of thrombus resolution. It is further disclosed herein that thataugmentation of p53 gene function can improve thrombus resolution.

There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofthat follows may be better understood, and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described furtherhereinafter.

In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of otherembodiments and of being practiced and carried out in various ways.Also, it is to be understood that the phraseology and terminologyemployed herein are for the purpose of description and should not beregarded as limiting.

As such, those skilled in the art will appreciate that the conceptionupon which this disclosure is based may readily be utilized as a basisfor the designing of other structures, methods and systems for carryingout the several purposes of the present invention. It is important,therefore, that equivalent constructions insofar as they do not departfrom the spirit and scope of the present invention, are included in thepresent invention.

For a better understanding of the invention, its operating advantagesand the specific objects attained by its uses, reference should be hadto the accompanying drawings and descriptive matter which illustratepreferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS AND THE FIGURES

FIG. 1 is a photograph taken during the execution of the mouse model ofthrombus resolution.

FIG. 2 is a photograph of the mouse model of thrombus resolution takenon post-operative day 3 illustrating the surgical ligature at the upperaspect of the vena cava and the large thrombus notable within the venacava.

FIG. 3 is a photomicrograph of a thrombus from the mouse model harvestedon post-operative day 3.

FIG. 4 is a photomicrograph of a thrombus from the mouse model harvestedon post-operative day 12.

FIG. 5 is a graph illustrating the resolution of thrombus in the mousemodel over time by comparing thrombus weights in animals at eitherpost-operative day 4 or 12 after thrombus formation.

FIG. 6 is an immunoblot showing increased expression of p53 proteinwithin the thrombus on post-operative day 12 in three animals thatunderwent thrombus formation (DVT, left) in comparison to three animalsthat underwent sham surgery (right).

FIG. 7 shows the impaired thrombus resolution in mice lacking the p53gene in comparison to normal (wildtype) mice as determined by thrombusweight on day 12.

FIG. 8 shows the effect of administration of the p53 activator,quinacrine, on thrombus resolution as assessed by thrombus weight on day12.

FIG. 9 shows the effect of quinacrine on thrombus resolution in normalmice (labeled control and quinacrine) and in mice lacking the p53 genewhich are labeled p53(−/−).

DETAILED DESCRIPTION OF THE INVENTION

In an effort to develop pharmacological and molecular therapy toaccelerate thrombus resolution, the function of the p53 gene was studiedin an in vivo model of thrombus resolution. In this mouse model (venacaval ligation) the thrombus shrinks between day 4 and day 12 by about50% as defined by change in thrombus weight. It was noted that theexpression of the p53 protein is increased in thrombus resolution.

p53, also known as protein 53 or tumor protein 53, is a tumor suppressorprotein that in humans is encoded by the TP53 gene. To define the roleof the p53 gene in the process of thrombus resolution, thrombusresolution in mice lacking the p53 gene was compared with normal(wildtype) mice. It was determined that mice genetically lacking p53 hadimpaired resolution of thrombus as defined by larger thrombi on day 12in comparison with wildtype mice. This demonstrates that the p53 geneplays an important role in thrombus resolution. Specifically, in thismodel lack of the normal p53 gene impairs thrombus resolution.

In order to determine whether augmentation of normal p53 function couldaccelerate thombus resolution wildtype mice were treated with the p53activator quinacrine (25 mg/kg body weight, by daily injection).Quinacrine is known to increase p53 levels by stabilizing the p53protein and preventing its normal degradation inside cells. Animalstreated with the p53 activator showed improved thrombus resolution ascompared with animals that were injected with saline alone.

To determine whether the beneficial effect on thrombus resolution ofquinacrine was due to activation of the p53 gene and not some otherunknown effect of quinacrine on thrombus resolution the quinacrineexperiment was repeated in mice that lack p53 (FIG. 2). Here it wasfound that the benefit of quinacrine on thrombus resolution was absentin mice lacking p53, thereby demonstrating that the accelerated thrombusresolution with quinacrine was mediated by augmentation of p53 activity.This shows that increasing p53 function in vivo results in improvedthrombus resolution, and is the first demonstration of augmentation ofthe p53 gene to achieve this goal.

It is therefore provided herein: a first demonstration of effectivepharmacological therapy to accelerate resolution of an establishedvenous thrombus; and experimental evidence that augmentation of p53 genefunction accelerates thrombus resolution. Varying means of augmentingp53 function including but not limited to gene transfer of p53, and theapplication of pharmacologic agents that increase p53 protein and/oractivity are known to one of ordinary skill in the art.

It is disclosed herein that administration of quinacrine in an in vivomodel of thrombus resolution results in accelerated resolution, and thatthis beneficial effect is dependent on activation of the p53 gene. Oneskilled in the art of medicine and pharmacology could systemicallyadminister quinacrine, or other activators of the p53 gene, includingbut not limited to chloroquine or other acridines, to accelerateresolution of thrombus in patients with arterial or venous thrombus. Oneskilled in the art of medicine and pharmacology could deliver activatorsof p53 via catheter or other local delivery device to areas of thecirculation involved with thrombus to provide high local concentrationof the agent to accelerate resolution of the thrombus. One skilled inthe art of medicine and pharmacology could deliver gene therapy (usingplasmid cDNA for p53, an adenovirus encoding p53 or a lentivirusencoding p53) to increase expression of the p53 protein in areas ofthrombus by a catheter, infusion balloon or other localized deliverydevice. Contemplated delivery means further include for example ap53-encoding nucleic acid in a recombinant vector that expresses p53protein. Such p53-expressing recombinant vector can include a naked DNAplasmid, a plasmid within a liposome, a viral vector or the like. Theviral vector can be for example a retroviral vector or a recombinantadenoviral vector. The p53-encoding nucleic acid can be provided in anexpression cassette. In one embodiment, the expression cassette canfurther include an SV40 early polyadenylation signal. The p53-encodingnucleic acid can be under the control of a constitutive promoter. Inexemplary embodiments the constitutive promoter can be a cytomegaloviruspromoter, RSV promoter, or SV40 promoter. For example, the constitutivepromoter can be cytomegalovirus IE promoter. In an alternativeembodiment at least one gene essential for adenovirus replication can bedeleted from the recombinant adenoviral vector. For example, the E1A andE1B regions of the adenovirus vector can be deleted and the p53expression cassette introduced in this region.

The well-established rodent model of thrombus resolution was used todefine a role for the p53 gene in this process. In this model, a mouseis anesthetized, the abdomen is opened with standard sterile surgicaltechnique and the vena cava (the largest abdominal vein) is ligated inthe abdomen with a suture immediately below the level of the renalveins.

FIG. 1 illustrates an intraoperative photograph of the vena cava wherethe suture is in position in the upper aspect of the image but has notyet been tied down. Ligation of the vena cava results in the predictablegeneration of a thrombus immediately below the ligature.

The thrombus increases in size for 3-4 days as shown in FIG. 2, which isan intraoperative photograph showing the thrombus within the vena cava 3days after the ligature was placed. The thrombus then decreases in sizefor the next 14 days and this resolution corresponds with infiltrationof the thrombus with inflammatory cells and collagen. This is shown inFIGS. 3 and 4, which are photomicrographs of thrombi harvested on day 3and day 12, respectively, where the cellular composition of the thrombihas greatly increased on day 12 (FIG. 4) in comparison to day 3 (FIG.3).

The weight of the thrombus decreases with time, and this change inweight reflects the thrombus resolution process in this model. Thisthrombus resolution is illustrated by FIG. 5, where the thrombus weight(normalized to the body weight of each animal at the time of sacrifice)is shown for thrombi harvested on day 3 and on day 12. The effects ofabdominal surgery alone (without formation of a thrombus) on the weightof the vein are shown by the clear bars labeled “sham”. There isapproximately a 50% decrease in the mass of the thrombus between day 3and day 12 (FIG. 5).

The expression of the p53 gene during the process of thrombus resolutionis illustrated by FIG. 6. As shown in FIG. 6, protein immunoblottingusing gel electrophoresis shows that protein extracted from threethrombi at day 12 (labeled DVT, left lanes) show more p53 protein thanthree vena cava harvested 12 days after sham surgery (labeled sham,right lanes). Sham surgery animals were used as controls to ensure thatany change in p53 protein levels would reflect the thrombus resolutionand not residual inflammation from the surgical procedure itself. Forthis experiment, proteins were extracted from the thrombi or vena cava,processed for western blotting using standard acrylamide gelelectrophoresis, transferred to nylon membranes and specifically probedwith a commercially available antibody specific for the p53 protein.

To determine whether the activation of the p53 gene noted duringthrombus resolution played any role in the process of thrombusresolution, thrombus resolution was studied in mice lacking the p53gene. When thrombus resolution was studied in these commerciallyavailable mice (and normal mice for comparison), it was determined thatmice lacking p53 had statistically larger thrombi on day 12, indicatingthat thrombus resolution was impaired in these mice (FIG. 7). Thisexperiment was done with groups of 5-8 animals per time point and wasstatistically significant using student's t-test comparison. Thesestudies demonstrated that the p53 gene plays a role during thrombusresolution. There was no significant difference between the normal miceand the mice lacking p53 in the size of the thrombi at day 3, indicatingthat the effect of p53 was specific to thrombus resolution and not theprocess of thrombus formation.

To determine if pharmacologic activation of the p53 gene beyond itsusual activation by thrombus resolution might accelerate thrombusresolution, normal mice were treated with the p53 activator quinacrine(25 mg/kg body weight, by daily injection) or saline as a control, andthen subjected to vena caval ligation as described above. It was foundthat quinacrine treatment accelerated thrombus resolution as determinedby decreased thrombus weight on day 12 (FIG. 8). To determine if thiseffect of quinacrine was actually due to p53 activation, this experimentwas repeated in animals lacking the p53 gene. The purpose of thisexperiment was to ensure that the demonstrated effects of quinacrine onthrombus resolution were due to activation of the p53 gene and not someother effect of the drug in the animal (so called “off-target effect”).

When quinacrine was administered to mice lacking the p53 gene (labeledas p53(−/−) in the graph), there was no difference in thrombus size atday 12 (FIG. 9, last two columns), demonstrating that the beneficialeffect of quinacrine on thrombus formation is dependent on the presenceof, and thus mediated by, the p53 gene. Together these experimentsdemonstrate: 1) activation of the p53 gene during the thrombusresolution process, 2) a role for the p53 gene in mediating the normalprocess of thrombus resolution, 3) activation of the p53 genepharmacologically results in improved thrombus resolution.

This invention demonstrates that pharmacologic augmentation of p53activity can be used to treat patients suffering from deep venousthrombosis with the potential to accelerate resolution of the thrombusand decrease secondary complications of the thrombus within the veinwall.

In one embodiment the aforementioned pharmacologic agents are applied toan intravascular device such as a stent, vascular graft or otherimplantable vascular prosthesis. The pharmacologic agent is covalentlybonded or otherwise chemically or physically attached to a stent,stent-graft, prosthetic graft, vena caval filter, artificial venous orarterial or cardiac valve, or other implantable vascular device for thepurpose of accelerating the resolution of thrombus either present at thetime of implantation or thrombus expected to develop post-implantation.Delivery systems are known by one of ordinary skill in the art andinclude but are not limited to controlled-release gel, biochemicalcoating, a p53 activator drug or gene delivery system (such as a plasmidencoding p53 gene), and the like.

Chemical modifications to known p53 activators (such as quinacrine) toprolong its pharmokinetic profile (such as half-life within the patient)or to increase its p53 activating ability are contemplated herein. Oneskilled in the art would test these modified compounds in the standardmodels of thrombus resolution (as shown in FIGS. 1-5) and could applythese to patients with either arterial or venous thrombosis for improvedtherapeutic efficacy or ease of drug dosing for the purpose ofaccelerating thrombus resolution.

Having now described a few embodiments of the invention, it should beapparent to those skilled in the art that the foregoing is merelyillustrative and not limiting, having been presented by way of exampleonly. Numerous modifications and other embodiments are within the scopeof one of ordinary skill in the art and are contemplated as fallingwithin the scope of the invention and any equivalent thereto. It can beappreciated that variations to the present invention would be readilyapparent to those skilled in the art, and the present invention isintended to include those alternatives. Further, since numerousmodifications will readily occur to those skilled in the art, it is notdesired to limit the invention to the exact construction and operationillustrated and described, and accordingly, all suitable modificationsand equivalents may be resorted to, falling within the scope of theinvention.

1. A method of accelerating the resolution of a thrombus in a subject orincreasing recanalization of a thrombosed artery or vein, comprisingadministering a therapeutically effective amount of an activator of thep53 gene to a subject suffering from arterial or venous thrombosis. 2.The method of claim 1, further comprising administering atherapeutically effective amount of an anticoagulant to said subject. 3.The method of claim 1, wherein said activator of the p53 gene isselected from the group consisting of quinacrine, chloroquine, and otheracridines.
 4. The method of claim 1, wherein said activator isadministered by way of a drug delivery device.
 5. A method ofaccelerating the resolution of an arterial or venous thrombus in asubject or increasing recanalization of a thrombosed artery or vein,comprising delivering to said subject therapeutically effective amountsof a p53-encoding nucleic acid.
 6. The method of claim 5, wherein thep53-encoding nucleic acid is in a recombinant vector that expresses p53protein.
 7. The method of claim 6, wherein the p53-expressingrecombinant vector is a naked DNA plasmid, a plasmid within a liposome,or a viral vector.
 8. The method of claim 7, wherein the viral vector isa retroviral vector or a recombinant adenoviral vector.
 9. The method ofclaim 7, wherein the p53-expressing recombinant vector is a recombinantadenoviral vector.
 10. The method of claim 6, wherein the p53-encodingnucleic acid is in an expression cassette.
 11. The method of claim 10,wherein the expression cassette comprises the p53-encoding nucleic acidunder the control of a constitutive promoter.
 12. The method of claim11, wherein the constitutive promoter is a cytomegalovirus promoter, RSVpromoter, or SV40 promoter.
 13. The method of claim 12, wherein theconstitutive promoter is the cytomegalovirus IE promoter.
 14. The methodof claim 10, wherein the expression cassette further comprises an SV40early polyadenylation signal.
 15. The method of claim 9, wherein atleast one gene essential for adenovirus replication is deleted from therecombinant adenoviral vector.
 16. The method of claim 15, wherein theE1A and E1B regions of the adenovirus vector are deleted and the p53expression cassette is introduced in their place.
 17. A method ofinhibiting thrombosis or accelerating the resolution of existingthrombus comprising: applying a therapeutically effective amount of anactivator of the p53 gene to an intravascular device prior toimplantation in a patient.
 18. The method of claim 17, wherein theintravascular devise is an implantable vascular prosthesis or vasculargraft.
 19. The method of claim 17, wherein said activator of the p53gene is selected from the group consisting of quinacrine, chloroquine,and other acridines.
 20. The method of claim 17, further comprisingadministering a therapeutically effective amount of an anticoagulant tosaid subject.